Multiple access control

The capacity of Gaussian broadcast MIMO channel can be improved with Dirty Paper Coding. In this paper, the mean capacity for
MU-MIMO (Multi-User Multiple Input, Multiple Output) is analyzed in terms of number of frames, available number of users at mobile station
and number of packets. The analysis is done for 4x4 matrix. Dirty Paper Coding improves the degradation due to correlation and mutual
coupling. In multi-user communication, multiple antennas allow users to transmit their data stream in the uplink and downlink

: In this work we propose and evaluate a multiple access control mechanism for the multiplexing and the integrated delivery of Voice, Video and Data Traffic over a Wireless Cellular High Speed Packet Switched Network. We focus on the uplink wireless channel and we ...

... On the design, implementation and application of an authorisation architecture for web services Sarath Indrakanti, Vijay Varadharajan* and Ritesh Agarwal ... Ritesh Agarwal received his Master of Technology degree from the Indian Institute of Technology (IIT), Roorkee, India. ...

Abstract - The article focuses on Call Admission Control (CAC) techniques proposed for multimedia UMTS systems employing Wideband CDMA. Multiple Access Control in CDMA is an interference management problem, involving physical layer as well as networking aspects. The effect ...

In this paper, the estimation of a scalar field over a bidimensional scenario (e.g., the atmospheric pressure in a wide area) through a self-organizing wireless sensor network (WSN) with energy constraints is investigated. The sensor devices (denoted as nodes) are randomly distributed; they transmit samples to a supervisor by using a clustered network. This paper provides a mathematical framework to analyze the interdependent aspects of WSN communication protocol and signal processing design. Channel modelling and connectivity issues, multiple access control and routing, and the role of distributed digital signal processing (DDSP) techniques are accounted for. The possibility that nodes perform DDSP is studied through a distributed compression technique based on signal resampling. The DDSP impact on network energy efficiency is compared through a novel mathematical approach to the case where the processing is performed entirely by the supervisor. The trade-off between energy conservation (i.e., network lifetime) and estimation error is discussed and a design criterion is proposed as well. Comparison to simulation outcomes validates the model. As an example result, the required node density is found as a trade-off between estimation quality and network lifetime for different system parameters and scalar field characteristics. It is shown that both the DDSP technique and the MAC protocol choice have a relevant impact on the performance of a WSN.

In this work, we study the efficiency of a new reservation medium access control protocol for wireless communications, named Multimedia Integration Multiple Access Control (MI-MAC), by comparing it with another well-known protocol for multimedia integration over wireless networks (DPRMA). Our scheme, one of the first in the literature that considers the integration of streams from latest technology video encoders with other types of packet traffic over wireless networks, is shown to outperform DPRMA* (a very slightly modified version of DPRMA, used in order to be able to make comparisons between the two protocols) in terms of aggregate channel throughput and mean Web data transmission delays.

The growing amount of multimedia data available to the average user has reached a critical phase where methods for indexing, searching, and efficient retrieval are expressly needed to manage the information load. In this paper, we present a hybrid video database model ...